Self rotating airplane tire

ABSTRACT

An aircraft tire is provided with circumferential grooves in the tread face, which grooves include as the floor thereof a series of impeller vanes defined by asymmetrical wedges which present differential resistance to the airstream at vertically opposed locations on the tire to cause the tire to be rotated by the airstream.

United States Patent 1 Abplanalp Nov. 20, 1973 SELF ROTATING AIRPLANETIRE [76] Inventor: Robert Henry Abplanalp, 700

Nepperhan Ave., Bronxville, N.Y. 10703 [22] Filed: Mar. 22, 1972 [21]Appl. No.: 237,113

[52] US. Cl. 244/103 S [51] Int. Cl. B64c 25/40 [58] Field of Search244/103 S, 103 R [56] References Cited UNITED STATES PATENTS 2,377,6386/1945 Lueck 244/103 S 2,403,309 7/1946 Smith 244/103 S FOREIGN PATENTSOR APPLICATIONS 1,160,467 7/1958 France 244/103 S 1,422,320 11/1965France 244/103 S Primary Examiner-Milton Buchler Assistant ExaminerPaulE. Sauberer Att0meyJames W. Bock [5 7] ABSTRACT An aircraft tire isprovided with circumferential grooves in the tread face, which groovesinclude as the floor thereof a series of impeller vanes defined byasymmetrical wedges which present differential resistance to theairstream at vertically opposed locations on the tire to cause the tireto be rotated by the airstream.

9 Claims, 2 Drawing Figures PATENTEUuuvzo I973 FIG.1

FIGZ

SELF ROTATING AIRPLANE TIRE The invention is concerned with an aircrafttire which is provided with means to cause it to rotate when exposed tothe airstream.

It is well-known that aircraft tires are subject to a great deal ofstress, wear and heating at the moment of touchdown. Starting withessentially no rotational velocity, aircraft wheels must be rapidlyaccelerated by frictional contact with the runway to a circumferentialvelocity equal to the high landing speeds of modern aircraft. Since someaircraft land at velocities on the order of 150 miles per hour, thewheel acceleration involved is quite substantial. The frictionalaccelerating force occurs simultaneously with the imposition of highwheel forces due to the mass of the landing aircraft. Some consequencesof this sudden acceleration are slip or scufiing resulting in uneventire wear, rapid heat buildup within the tire, and danger of skidding.The scuffing of the tire and heat buildup caused by the rotationalacceleration during landings significantly shortens the life of thetire. The stress occasioned by the acceleration of the aircraft wheeland tire is ultimately transmitted to the landing gear, requiring thatit sustain this stress in addition to the others of landing.

Various means have been proposed for attempting to impart spin toaircraft wheels prior to touchdown.

Some techniques for causing tire rotation are disclosed in U. S. Pat.No. 3,233,849 issued to Rubin and No. 2,435,801 issued to Shively. Thedisclosed techniques include providing flaps or pockets on the tiresidewall which trap air and thereby cause tire rotation when the tire isexposed to the airstream. U. S. Pat. No. 2,417,466 issued to Brewerteaches forming flaps or pockets incorporated into the tread face of thetire. U. S. Pat. No. 3,532,147 to Gough et al describes an aircraft tirehaving a plurality of circumferential grooves in the tread face with thesurface contacting faces of the tread being provided with recesses orpockets having water outlets leading to the circumferential grooves. TheGough et al tire is designed to be rotated by water, through theutilization of a turbine-like effect if the tire skids or aquaplanes inlanding on a wet runway.

It is the object of this invention to provide an improved aircraft tirewhich self-rotates when exposed to the airstream, which otherwise equalsthe performance of ordinary aircraft tires, and which is easily moldedon conventional equipment.

The tire herein disclosed avoids the uneven heat buildup in the tiresidewall occasioned by the varying thickness and heat transfercharacteristics inherent in flaps on the sidewall. Since the tire of thepresent invention has a conventional runway contacting tread face, itwill be as quiet and vibrationless in operation as conventional aircrafttires. Unlike tires having interrupted tread faces, the tire of thesubject invention provides adhesion equal to conventional aircraft tireslacking self-rotating features. The capability of self-rotation will beretained undiminished throughout the useful life of the tire because therotation imparting means are not in wearing contact with the runwaysurface. As the tread surface wears, the self-rotation means begin tocontact the runway and cause noise and vibration which give an audibleindication that the useful tread is expended. Unlike the self-rotatingtires of the prior art, the tire of the present invention is easy tomold with conventional equipment. There are no flaps, interior voids, orwater channels, each of which requires complex molds.

The invention will now be described in detail, with reference to thedrawings wherein:

FIG. 1 illustrates a circumferential cross-section of a tire embodying aform of the invention taken along the plane I-I of FIG. 2; and

FIG. 2 illustrates a radial cross-section of the embodiment of FIG. 1taken along the plane II-II of FIG. 1.

In the embodiment illustrated in FIGS. 1 and 2, there is shown a tire 2having a plurality of circumferential tread grooves 4. Within eachgroove, and forming the floor thereof, is a series of asymmetric wedges8 of generally saw-tooth configuration, each of the wedges having aradially disposed face 14 and a longer sloping or tangential face 10.The apex 16 of each of the wedges lies in a circle having a radius R-lless than the radius R2 of the contact surface of the tread face 6, suchthat there is an annular gap 18 between the outermost apex portion 16 ofthe wedges and the tread face 6. The wedges are of a width correspondingto the width of the circumferential grooves 4. The longer face 10 ofeach wedge and the radial face 14 of the neighboring wedge together forma complementary wedge shaped recess or pocket 12. The radial faces 14act as impeller vanes against which the airstream impinges with anappreciably greater momentum transfer than that at the verticallyopposite longer sloping faces which present a lower air resistanceaspect to the oncoming airstream.

In use, the tire is positioned with respect to the airstream such thatthe radial faces 14 of the wedges 8 are perpendicular to and face theairstream at the bottom of the tire, and the longer sloping faces 10 arepresented generally parallel to the airstream at the top of the tire.Consequently, there is a greater impact pressure and greater momentumtransfer resulting in a commensurately greater force at the radial face14 at the bottom than at the face 10 at the top. This results in adifferential of air resistance forces at vertically opposed locationswhich causes tire rotation in the direction of aircraft travel prior totouchdown. This rotation automatically begins when the landing gear islowered into the airstream. The wheels gradually accelerate to acircumferential velocity which may be less than the landing velocitybecause of frictional losses, but is a useful fraction thereof. Thisgradual acceleration lessens the stresses on the tire and landing gearat the moment of touchdown. The airstream induced rotation reduces theinitial deceleration lurch of the aircraft as well as tire wear, tireheat and landing gear stress. Under wet runway conditions, the radialfaces 14 of the wedges 8 are acted upon by the water to reduce thesliding effect called aquaplaning. The wedges tend to keep the tirerotating as the aircraft rolls through water. The wedges 8 are spacedfrom the runway surface by the annular gap 18. The gap 18 diminishes asthe tread 6 wears until the wedges 8 contact the runway. This wedgecontact creates a noise which serves as an audible signal of the need toreplace the now worn tire.

Although the preferred embodiment is described as having wedges withradial faces 14 and tangential faces 10, it is apparent that the wedgefaces could depart from purely radial or tangential attitudes and couldbe of non-planar shapes. The particular face shapes chosen must beasymmetric to display differential air resistance between thediametrically opposed upper and lower portions of the tire to yield arotational force.

I claim:

1. An airstrearn rotatable aircraft tire having a tread face includingat least one circumferential groove, the groove wholly containing aplurality of fixed impeller vanes of an asymmetrical shape whichpresents differential resistance to the airstream to cause rotation, theradially outermost extent of said vanes being radially inward of thetread face.

2. The tire of claim 1, wherein said impeller vanes define the bottom ofthe groove.

3. The tire of claim 2 wherein the impeller vanes are in the generalform of wedges having a generally radial face and a second face.

4. The tire of claim 3 wherein the second face slopes and extends fromthe generally radial face of one wedge toward the generally radial faceof the adjacent wedge of the series of vanes.

5. The tire of claim 4 wherein the second face of a wedge intercepts theradially outermost extent of the generally radial face of that wedge andis generally perpendicular to the radially innermost extent of thegenerally radial face of the adjacent wedge.

6. The tire of claim 5 wherein said second face is longer than saidgenerally radial face. 7

7. The tire of claim 6 wherein the tread face includes a plurality ofsaid circumferential grooves.

8. The tire of claim 7 wherein the radial face and the second face areplanar.

9. An aircraft tire with a tread face having at least onecircumferential groove which includes fixed rotation imparting meanswhich present differential resistance to the airstream at verticallyopposed locations to induce rotation, the radially outermost extent ofsaid fixed rotation imparting means being radially inward of the treadface.

1. An airstream rotatable aircraft tire having a tread face including atleast one circumferential groove, the groove wholly containing aplurality of fixed impeller vanes of an asymmetrical shape whichpresents differential resistance to the airstream to cause rotation, theradially outermost extent of said vanes being radially inward of thetread face.
 2. The tire of claim 1, wherein said impeller vanes definethe bottom of the groove.
 3. The tire of claim 2 wherein the impellervanes are in the general form of wedges having a generally radial faceand a second face.
 4. The tire of claim 3 wherein the second face slopesand extends from the generally radial face of one wedge toward thegenerally radial face of the adjacent wedge of the series of vanes. 5.The tire of claim 4 wherein the second face of a wedge intercepts theradially outermost extent of the generally radial face of that wedge andis generally perpendicular to the radially innermost extent of thegenerally radial face of the adjacent wedge.
 6. The tire of claim 5wherein said second face is longer than said generally radial face. 7.The tire of claim 6 wherein the tread face includes a plurality of saidcircumferential grooves.
 8. The tire of claim 7 wherein the radial faceand the second face are planar.
 9. An aircraft tire with a tread facehaving at least one circumferential groove which includes fixed rotationimparting means which present differential resistance to the airstreamat vertically opposed locations to induce rotation, the radiallyoutermost extent of said fixed rotation imparting means being radiallyinward of the tread face.